Advances in machine design, especially robotics, have enabled precision operations in a fully automated context. The present invention, while developed in conjunction with engraving applications has many uses wherein rigid, precise and play-free registration of a workpiece must be made relative to a working member, without damage to the workpiece surface. One example of such an application is found in U.S. Pat. No. 4,561,814, which describes a mechanical engraving table having a slotted surface whose slots permit a first iteration of workpiece positioning.
The present invention provides a clamping device for use in conjunction with a slotted working table. This clamping device is particularly useful for rigidly registering plate-type workpieces relative to a working member, e.g., an engraving bit. The clamp, by virtue of a spring-biased nosepiece with a stepped surface on one end and stepped workpiece receiving surfaces as an integral part of the other end, is easily adjustable for a wide range of plate thicknesses and plate sizes. Further, the clamping device engages the workpiece in a non-destructive manner, leaving the plate free of markings. The clamping device of the present invention provides sufficient rigidity to resist the torque forces generated by the engraving bit as well as to maintain accurate positioning of the workpiece as the working member contacts the workpiece. The clamping device is also capable of handling irregularly shaped workpieces. Furthermore, the clamping device is able to achieve high throughput because the device is simple to operate, fastening and releasing work pieces by the mere turn of the screw.
The clamping device according to the present invention is different from conventional clamps in several ways. Many vices and clamps presently available are substantially larger than the clamp presented here. However, most of these clamps are not capable of clamping workpieces as large. The clamp of this invention can be used to clamp pieces nearly as large as the slotted work station with which this clamp is used. Further, this clamp does not have to fit onto any particular section of the work station. It can be secured almost anywhere on the work station. This clamp is also easily moveable.
Many of the clamps now available commercially hold the workpiece by securing it between two clamp bars. These clamps provide no support for the top of the workpiece. The instant clamp secures the top surface of the workpiece as well as its sides, the stepped working surfaces disposed at an acute angle to the workpiece, and the spring-biased nose pushing the workpiece downward and against the work station surface.
Unlike most other clamps, the instant clamp is designed for a T-slot table. A slot through the clamp member spans nearly two-thirds of its length, receiving a screw which cooperates with the T-nut assembly to secure the clamp and the workpiece to the surface of the work station. This creates a force perpendicular to the working surface.
Therefore, it is an object of this invention to provide a clamping device for use in combination with a slotted working surface which is simple to position and reposition.
It is a further object of this invention to provide a clamping device which is sufficiently rigid and precise for engraving procedures.
It is a still further object of this invention to provide a clamping device which is adaptable to a variety of workpieces.